I was actually writing a completely unrelated feature request and while writing it I noticed it's already possible, however I noticed that SO doesn't actually do anything at all if one of my tags doesn't have any questions in it anymore. Here's what I'd propose as possible solutions for cases such as these:

Provide UI feedback when tag is deprecated

In this context deprecated means depleted out of questions. In this particular case, the tag postgresql used to have a bunch of questions but apparently they had been all retagged under postgres making postgresql obsolete/deprecated. It would've been nice for the UI to pop up a notice about this so that I could've replaced the tag as soon as such action became relevant instead of now after for how long this has really been the case.

Add a way for users with high enough karma to redirect tags

By allowing users to create automatic replacements to deprecated tags SO could support automatic changing of the deprecated tag to whatever it should really point to. This way only one person or a relatively small group of persons would really need to do the change and it would propagate itself to the entire user base.

Allow for metaranking/-linking of tags.

There may be completely valid reasons to keep some of the tags but as far as I'm concerned, I wanted to notice the postgres questions even though I had selected postgresql. If we are allowed to metalink tags (once again, by user with respectably high karma), the system could automatically help me manage my tags with the Google-esque "Did you mean someothertag?" type of feedback message or some other non-intrusive method.

UPDATE @ 16 Nov 2009

Well, now someone has changed them the other way around again! Or maybe some time ago, can't really tell, this is extremely annoying!

1 Answer
1

The system already tells you how many questions a tag has associated with it at the time you add the tag to you question. It's the number in parentheses after the name of the in the little look-ahead prompt you see when tagging your question. Any time you see a number less than 10 or so there, you probably want a different tag.

However, I agree a little more discouragement from using those tags would nice.

That's the thing, when I originally added the tag, it had hundreds of questions - not anymore! That's what I'm really after here, notification when the condition of the tag itself changes significantly, ie. someone removes it from all the questions.
–
EskoSep 14 '09 at 18:50

Big flashing "X"s should appear on screen. And smoke should leak out the fan port.
–
devinbSep 14 '09 at 18:52

2

There is a cache of this information. If there was a recent moderator re-tag, the numbers will be way off until the cache is updated.
–
Brad GilbertSep 14 '09 at 18:53

This isn't a caching issue either, after cache has been repopulated one could see if the tag is used anywhere or not. I'm not saying the alert/action should be instant, it'd be nice if SO would point it out at some time after the change has been made instead of the current "maybe the user notices it at some point by himself, maybe".
–
EskoSep 19 '09 at 8:55